This invention relates to high voltage power transmission line metering systems, and more particularly to a filtering system and module for enhancing data communication about and on power transmission lines.
One of the problems encountered by electric public utilities in the transmission and distribution of electrical power through their high voltage power transmission system and network is the loss of power by theft from various locations along their sub-branch distribution lines of the network where power is connected to the ultimate consumer. For example, it has been reported that an electric public utility serving various remote areas of British Columbia in Canada has experienced loss by theft of a considerable quantity of electrical power to illegal marijuana growing installations. Such illegal growers have been known to buy or just move as squatters into an abandoned building. They then reconnect the existing disconnected power service line to their building power service lines in order to illegally provide electrical power service to their greenhouse operations for growing marijuana. Short of actually patrolling and inspecting all customer metering installations along the branch distribution lines, including such disconnected installations at abandoned sites, it has not been economically feasible to remotely pinpoint the geographic location where such power theft losses are occurring. Although the amount of power being distributed over a given sub-branch transmission line is metered by transmission line watt meters, due to excessive xe2x80x9cnoisexe2x80x9d in the line, i.e., 60 cycle xe2x80x9chumxe2x80x9d, it has not been possible to remotely telemeter an individual meter on the power transmission line to determine or pinpoint the location along sections of sub-branch lines that are showing excessive power loss to unauthorized power hook-ups.
In one approach to solving the forgoing power line theft telemetering problem, it has been proposed that the power transmission line be directly filtered to eliminate the interfering noise in the transmission line signal. It is then believed it would be possible to be able remotely identify, by comparative meter data transmitted, the particular geographic location where utility personnel could be directed to look for power theft along the sub-branch line in order to apprehend the thieves and stop the power loss in a timely and efficient manner.
In order to accomplish the electrical noise filtering process proposed hereinabove, it has been further proposed to provide a straight forward filter network between the typical 15 kilovolt electrical power distribution line and an associated watt meter operably connected for sensing the rate of power consumption along such line. Such filter/meter installations would be located at strategic predetermined locations along the power distribution network in order to limit the geographical extent of indicated theft searching to a reasonable geographic area and distance along the line. Such installations would be pole mounted and thus must necessarily be able to withstand the adverse environmental conditions of outdoor powerline equipment and operate in a reliable manner without service for an extensive service life of say up to 100 years.
A proposal for a filter in such a system having the required electrical capacitance and inductance contemplates the provision of a series of cylindrically wound capacitors (or xe2x80x9ccondensersxe2x80x9d) that are of limited maximum size in order to be economically producible. Therefore a plurality of such capacitors are to be connected in series to provide the required total capacitance of the capacitive element in the filter circuit.
The inductance contemplated comprises a coil subassembly composed of an annular ferrite core with a primary winding wound on one portion of the core and having an input terminal connected to the output terminal of the array of capacitors and an output terminal connected to ground. The ferrite core would also serve as the flux link to a secondary winding also wound on the ferrite core and having its opposite terminals connected either to an appropriate watt meter or the like provided in close proximity to the filter or to some other digital communication device adapted for remote telemetering. However, the foregoing proposals did not provide a solution to the problem of how to economically construct a high voltage filter module embodying the capacitive and inductive components in a rugged, compact, durable, weather proof and reliable module. Accordingly, it is this latter problem and its solution to which the present invention is directed.
Accordingly, among the objects of the present invention are to provide an improved electrical filter network or circuit component module that is rugged, durable, difficult if not impossible to disassemble and that is reliably operable for use as a frequency filtering unit to filter out interference signal xe2x80x9cnoisexe2x80x9d from electrical power transmission lines, and particularly, from outdoor electrical utility sub-branch distribution lines so that such filtered signals can be fed to an associated watt meter, volt meter or other digital transmitting units for remote monitoring of customer-metered power consumption versus power loss along the power transmission line.
Another object is to provide an improved module of the foregoing character that provides a holder and protective container for the operative electrical components of the filter network and that allows them to be initially assembled and held for making soldering or other electrical connections between the individual components, that will hold the components in a predetermined array suitably spaced a predetermined distance from one another as well as the container walls in order to enable an electrically insulative and adhesive potting compound to be infilled in a liquid state and then solidify (cure) to thereby provide not only necessary extra electrical insulating properties but also bonding of the components as a solid unit and to protect the components from harsh application environments while at the same time adherently bonding all of the assembly frame parts and related housing cover and cap parts including solder joints.
A further object is to provide an improved module of the foregoing character and improved method of constructing the same that supports and accurately establishes the relative positions of all internal electrical components both during subassembly shipment, circuit component testing and for the duration of the useful life of the module regardless of serious abuses to the module both from outdoor environmental conditions and rough handling during shipment, storage and installation.
Another object is to provide an improved filtering module of the above character and associated telemetering instrumentation in combination with appropriate power line transmission equipment and telemetering instruments in an electrical power distribution system that is operable to adequately electrically filter the electrical power transmission line noise so as to be able to communicate with individual meters and telemeter their condition remotely.
A still further object is to provide a filter module system of the foregoing character that enables the power transmission line to be electrically filtered so as to remove sufficient unwanted and interfering noise in the transmission line to thereby enable digital data to be transmitted over the transmission line so that digital hardwire communication may be enabled to many remote geographic areas that do not have telephone lines or fiber optic lines.
In general, and by way of summary description and not by way of limitation, the invention achieves one or more of the foregoing objects by providing an improved filter assembly module comprising a cylindrical housing initially open at its opposite ends as made. A chassis component is disposed within the housing and has a planar base with a profile configuration adapted to contact the inner wall of the housing for centering the chassis radially in the housing. The chassis has at least one spindle rod extending within the housing parallel to the longitudinal axis of the housing and perpendicular to the major plane of the base of the chassis. One or more cylindrical spool-wound capacitors are mounted on the spindle rod by having the spindle rod extend axially through a spool-formed central through-passage of the or each capacitor. A position stabilizer is mounted on the spindle rod on the side of the capacitor remote from the chassis base, and also has a profile configuration adapted to contact the housing inner wall. An inductance coil component is disposed beneath the chassis base and held initially in assembly therewith by a plurality of short rods protruding from the base. A bottom cover is secured to and closes the bottom end of the housing so as to enclose therein the inductance coil component, the short rods and a retainer held by the rods. A top is cap secured to the top end of the housing and closes the same. Electrical circuit connector means extend through the cap and are operably and electrically coupled to the capacitors and inductance coil component, and also provide a ground connection as well as an inductively coupled output signal for coupling to an associated meter or the like. The interior space defined between the interior walls of the housing, cover and cap and the exterior surfaces of the capacitor and inductance coil component as well as the exterior surfaces of the chassis, position stabilizer and retainer are totally immersed and engulfed in a solidified thermosetting dielectric insulation material cast in-situ in the housing, cover and cap.
Preferably the chassis has three of such spindle rods extending parallel to one another and spaced apart with their longitudinal axes oriented in a equilateral triangle array. Preferably the capacitive component comprises three sets of a plurality of spool-wound capacitors electrically coupled in series and spindle supported one set on each the spindle rods. Preferably the inductance coil component comprises an inductor in the form of an annular core having a primary winding thereon with its opposite leads coupled one to the output lead of the series coupled capacitors and the other connected to ground. A secondary winding on the core has its opposite ends forming output leads adapted for coupling to the input terminals of the associated metering device or other digital communication device.
Preferably the foregoing filter module is constructed by a novel method wherein the capacitor and inductance components are first assembled to the chassis and then the unoccupied space enclosed by the bottom cover alone is filled with potting compound in a liquid state. Then the lower end of the housing is seated on the cover and is immersed at its lower edge in the potting compound filling the cover. Then the housing is filled with potting compound to engulf the capacitor components therein while being held on spindle rods. The housing potting material likewise engulfs the chassis structure disposed within the housing as the housing is so filled to its upper end brim with the potting compound. Then the electrical leads are trained through the cap and the cap is mounted on the upper end of the housing. Then the space within the cap is infilled with additional potting compound to thereby finish filling with potting compound the entire space enclosed within the said housing, cover and cap.